In recent years, a large number of light-emitting elements used for display devices and the like each have a structure in which a layer including a light-emitting substance is sandwiched between a pair of electrodes. Such a light-emitting element emits light when an excited electron, which is formed by a recombination of an electron injected from one electrode and a hole injected from the other electrode, returns to a ground state.
A large number of these light-emitting elements have a problem in that the driving voltage is increased with the accumulation of light-emission time.
In order to solve this problem, for example, the patent document 1 discloses an organic EL element using a compound with a certain structure, wherein the increase in driving voltage, and the like are suppressed in driving the organic EL element.    [Patent Document 1]: International Publication WO98/30071